The phenomena that the researcher is studying, trying explain or predict.
Or more simply…. the outcome that changes.
Our most common dependent variable is….. what do you think?
Crime!!!!!!!!
Independent Variables
A factor of characteristic that is used to try to explain or predict the dependent variable.
Or more simply… the characteristic that Influences
These range to all sorts of things (e.g., hunger, being inebriated, having mental disposition like psychopathy) and are most commonly the backbone of a theory.
Empirical
Having the qualities of being measurable, observable, or tangible.
Empirical phenomena are detectable with senses such as touch, sight, or hearing and they give rise to questions about the underlying forces driving them.
Pop Quiz
Identify the correct choice after reading the question below.
A police department collected data on gun crime incidents within each city in Nebraska, they hypothesized that a change would occur after the a recent protest within the city of Omaha.
What response best describe gun crime incidents
A.) it is an independent variable and a constant
B.) it is an independent variable and not a constant
C.) it is the dependent variable and not a constant
D.) it is the dependent variable and a constant
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Relationships Between Variables: A Cautionary Note
Independent and dependent variables are not synonymous with cause and effect.
An independent variable might be related (or correlated with) a dependent variable but this does not mean that are causally related.
Ok, then how do we determine a causual relationship?
What is a causal relationship?
A Causal effect is when variation in one phenomena the independent variable leads to variation in another phenomena the dependent variable..
\[ X-> Y\]
Temporal Ordering or Time Order
The independent variable must occur prior to dependent variable.
Empirical Relationship or Association
The independent and dependent variable must have some observed association.
In other words, if there is an change in one variable (X), there must be a change in another variable (Y).
Non-spuriousness or Controlling for Confounders
The relationship between the independent variable and the dependent variable is not the result of a third un-accounted variable.
This generally occurs due to omitted variable bias.
For example, the association between an increase in ice cream sales and increase in crime.
What is the omitted variable?
Recap
Variables
Constants
Three Rule for Causality
Levels of Measurement
A variables specific type or classification.
There are two classes of variables - continuous or quantitative and categorical or qualitative.
Wihtin the two classes there are Four Levels:
1.) Nominal
2.) Ordinal
3.) Interval
4.) Ratio
Nominal Variables
Categorical level of measurement
Ordinal Variables
Categorical but acts quantitative because of rank.
Interval Variables
Continuous but lacks a fixed zero point.
Ratio Variables
Continuous and has an absolute zero point.
Attributes of Measurements
Mutually exclusive attributes
Exhaustive attributes
Pop Quiz
You are a researcher at a think-tank compiling data on the amount of violent incidents in order to create a rank the most dangerous cities in America. What level of measurement is your dependent variable?